Aircraft: A321
Phase of flight: Descent
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence

On arrival descending through 6;000 feet received BARO degraded message. All 3 altimeters set exactly the same and correct to ATIS report. Few seconds later; AUTO FLT FCU 1 Fault. Captain PF (Pilot Flying) and lost auto pilot; auto thrust; flight directors both basically raw data. Selected FPV (Flight Path Vector) and made sure Captain was stabilized at about 5;000 feet. We were cleared to 4;000 feet. Advised ATC and immediately started working the problem with QRC; QRH. Challenging as we were in and out of tops trying to find good VMC box; bumpy. Worked problem; eventually fault reset and we landed uneventful. FCU1 -BARO FAULT cascade to complete auto flight failure's; into IMC. Descent given 7;000 feet; then 4;000 feet; then 270 base turn. ECAM AUTO FLT FCU 1 FAULT check BARO instruction. Crew check 3 BAROs set correct at 29.93. CA (Captain) directed ECAM ACTION for FOLLOWUP; cascade failure loss of AUTO FLT.A/THR; AP OFF; FCU 1&2; FADEC 1&2; EIU 1&2. Reported avionics loss to TRACON. Requested stop decent at 5000 ft. narrow VMC layer; denied due to traffic. Complied with immediate descent. Reported 4000 ft.; given north vector as requested to work problem.[Advised ATC]; SOB (Side of Body) and fuel 121 minutes. QRH FOLLOWUP. FO (First Officer) up to verify CB's (Circuit Breakers) for reset. Initial QRH computer reset attempt of FCU (Flight Control Unit) ineffective; added loss of NAV GPWS TERR DET FAULT. FO reported 7 minute wait for reset; given 5;000 feet and turns. PF (Pilot Flying) requested intercept to approach 5;000 feet cleared for XXL ILS approach; expecting raw data approach. NAV display after failures was now on 360 range with large HDG (heading) Rose; XXL approach including [arrival] displayed but very condensed. Range was selected. Probably selected Rose as TTT active in VOR1 during STAR; my habit; for backup position awareness. FMGC showed XXL from ZZZZZ but not active. Thankfully in this case; IAW (In Accordance With) FM1; in cruise I require the all profile approach intermediate waypoints be loaded and briefed when it follows a Discontinuity/HDG; loaded from database using Disc/Dest/Apch/NoStar method After we both confirm STAR waypoints; and this often allows correct published speeds to be managed by extending distance to runway.Airbus programing; only gives one prior to FAF; hope new change coming corrects that fact and loads APPCH as publish. CFIT or airspace intrusions unlikely with all restrictions displayed. ATT (Attitude Mode) indicated FPV (Flight Path Vector) and speed tape w Flaps 1 limits. FO completed QRH reset; returned to seat 2nd time.Within couple minutes and just prior to LOC CAPTURE; AP; A/THR and displays returned. Selected APPCH; AP 1 &2; Engaged A/THR (Auto throttles); observing full CAT 3 capable systems; after established. BARO still 29.93. PA to passengers in general about delay and currently on final approach for normal landing. Thanked for their patience. 1;000 feet. VMC; AP (Auto Pilot) disconnect and normal landing; thermal analysis and visual on ground; reported no exterior problems. Thanked and debriefed responders after arrival at gate. During taxi; informed Operations; requested call to Dispatch to report [advising ATC]; and avionics loss inflight. Request to Maintenance for avionics to meet at gate for debrief of failures. Took an hour for full debrief of AML and inflight events with avionics maintenance leads. Fleet CA called to relay inflight events for maintenance follow up supervision; discussion post-flight revealed a number of factors. FCU1 fault; why was FCU2 not activated/availableUnknown how a BARO fault would cascade through AUTO FLT including A/THR while FMGC display seemed good. QRH; for initial ECAM. Inflight reset did not work for current complete AUTO FLT failure; not surprising. 7 minute delay and reset of both FCU 1/2 incorrectly applied inflight; indicated for on ground procedure. Obvious unintentional mistake during circumstances. FO acknowledged post flight on review; thumb covered? This was a mistake and make no claim to knowledge or thinking it might work; ie. experimenting. QRH seems to not cover our faults; reset for initial fault seemed reasonable. Choice was to do FOLLOWUP reset or ignore QRH and fly basic as we were; still think delay vectors for stable approach was reasonable vice press in IMC from base turn. Really; it was awhile to transition and understand what was accurate information; while flight control crosschecking Standby reference's. Due to BARO fault and it's effect on FMC APPCH data; was not Sure ILS/LOC was there or if LS Comm selection going to be needed. Reset occurred before required action. Made no selections on FMGC after initial fault; fully occupied and did not want to risk loss due to BARO fault unknowns.On ground procedures in MEL; only preventive measure that would prevent our mistake; in flight. But understand; there are in flight procedures in MEL needed to ignore ECAM procedure. Airbus crosses both conventions for reason. Risk is greatest without AP; obviously; while PM (Pilot Monitoring) is solo confirming CB actions.Airbus Fleet CA stated similar fault events and would involve Airbus; hopefully develop useful fault corrective action for future. A321 flight crew reported that on initial approach they had a cascade of failures including auto flight.